Explanation:
Did you see that flash?
Lasting only about 15 seconds, it's possible
that nobody you ask can confirm it,
but what you might have seen is
sunlight reflecting off an orbiting
Iridium satellite.
Satellites of all types have been providing
streaks and glints visible only since the launch of
Sputnik I in 1957.
Of these,
flares from any of the
66 Iridium satellites can be particularly bright,
sometimes even approaching the brightness of the
Moon.
If the
Iridium satellites are programmed to
re-enter the Earth's atmosphere,
they might provide even brighter flares as they burn up.
Pictured above, the streak from an
Iridium satellite punctuates a picturesque sunset in
San Sebastian,
Spain.
Then again, that sky-flash you saw? If it lasted only a
second or two, it might have been a
meteor.